Americans Phil Mickelson and Davis Love will take a slim lead into the final round of the USPGA at Baltusrol.
The duo are six under, after Mickelson endured a frustrating two-over par round of 72 and Love shot a 68.
The undoubted star of the day was Dane Thomas Bjorn, who moved within a shot of the lead with a 63, equalling the best ever score in a major.
And Tiger Woods, who started the round 12 shots off Mickelson, is now only six shots behind after an impressive 66.
Defending champion Vijay Singh of Fiji lurks two shots off the lead on four under, along with former champion Steve Elkington of Australia, American Pat Perez and another Australian, Stuart Appelby.
Mickelson began the day three shots ahead of the field at eight under.
But it quickly became apparent he was struggling for form as he struck three bogeys in the first six holes to reach the turn in a three-over-par 37.
He managed to pull things together on the back nine with a 35 but could still not prevent Love - who claimed six birdies during his round - from taking a share of the lead.
Mickelson admitted he was pleased to still be leading the USPGA after his awful start to the third round.
"It was a fight for me to stay in the lead," he said. "After the start I had, to be still in the lead is a huge boost.
"It is a huge success for the day. Sunday is going to be a fun day, we are in the last group and we know what we have to do."
Love, who has only got one major to his name so far in his career, said he was confident going into the final round of the USPGA. "I'm confident and excited about the way I'm playing and looking forward to the next round. I'm starting to get that feeling again," Love said.
"It would mean a lot (to win). You obviously arrogantly think if you win one that the rest of them are easy."
Bjorn soared 33 places up the leaderboard with a stunning round that included eight birdies and only one dropped shot.
Nottinghamshire duo Lee Westwood and Greg Owen, who were paired together in the third-last group, remained in contention at three-under for the tournament.
Westwood, who started the day tied in third, salvaged a disastrous start to finish only one over for the round with 71, while Owen shot a level-par 70.
America's Jerry Kelly, who started the day in second place, slipped out of contention with a 74.
John Daly, the 1991 champion, also had a disappointing day, shooting an eight-over-par 78.
His cause was not helped by using a wedge instead of a putter on the last seven holes, after the head of his putter came loose.